This invention relates to a method for the deposition of a uniform layer of dry fibers on a forming surface of a foraminous forming wire member.
In prior art distributors such as is described in U.S. Pat. No. 3,581,706, a stream of gas containing fibers is fed into a housing having a perforated plane-surfaced bottom wall; impeller means mounted in the housing for rotation above the upper surface of the perforated wall circulates the stream of fibers in the housing. A foraminous forming surface on a wire member or the like moving beneath the distributor housing and the bottom wall of the housing receives under the influence of vacuum the fibers from the stream to form a fiber layer or web on the traveling foraminous wire member. The vacuum is commonly applied to the foraminous wire member and perforated wall to draw the fibers to the wire member and to separate the gas, usually air, from the fibers. The combination of the perforated bottom wall and the impeller means positioned closely above the surface of the bottom wall serve to, in effect, sift the fibers through the bottom wall to the foraminous member.
A primary object of this invention is to provide a method which improves the uniformity of the deposited fiber web.
A further object of this invention is to provide for a determination of the variations which may occur in the operation of equipment producing fibrous layers in a dry forming procedure, and to further provide a method of minimizing such variations.